diff --git a/numerical/max_sub_array.go b/numerical/max_sub_array.go
new file mode 100644
index 0000000..aaf80db
--- /dev/null
+++ b/numerical/max_sub_array.go
@@ -0,0 +1,31 @@
+package numerical
+
+import (
+	"fmt"
+)
+
+/* O(n) solution for calculating maximum subarray sum. */
+func Max(x int, y int) int {
+	if x < y {
+		return y
+	}
+	return x
+}
+
+func maxSubarray(array []int) int {
+	var currentMax int = 0
+	var maxTillNow int = 0
+	for _, v := range array {
+		currentMax = Max(v, currentMax+v)
+		maxTillNow = Max(maxTillNow, currentMax)
+	}
+	return maxTillNow
+}
+
+func main() {
+	array := []int{-3, -4, 7, 1, -2, 0, -5, 1, 0, 6, -5}
+	fmt.Println("Maximum subarray sum: ", maxSubarray(array))
+
+	array = []int{3, 4, -7, 2, 0, 0, -3, -1, 0, -5, 7}
+	fmt.Println("Maximum subarray sum: ", maxSubarray(array))
+}